001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    package org.apache.tapestry.enhance;
015    
016    import javassist.CtClass;
017    import org.apache.hivemind.ApplicationRuntimeException;
018    import org.apache.hivemind.service.ClassFab;
019    import org.apache.hivemind.service.ClassFactory;
020    import org.apache.hivemind.service.InterfaceFab;
021    import org.apache.tapestry.event.ResetEventListener;
022    
023    /**
024     * Implementation of the hivemind core {@link ClassFactory} service to get around some incompatibilities 
025     * the current 1.1.1 implementation of hivemind has with the latest (3.4) version of javassist. 
026     */
027    public class ClassFactoryImpl implements ClassFactory, ResetEventListener {
028        
029        static final int EXPIRED_CLASS_COUNT = 120;
030        
031        /**
032         * ClassPool shared by all modules (all CtClassSource instances).
033         */
034        private HiveMindClassPool _pool = new HiveMindClassPool();
035    
036        private CtClassSource _classSource = new CtClassSource(_pool);
037    
038        int _classCounter = 0;
039    
040        public ClassFab newClass(String name, Class superClass)
041        {
042            try
043            {
044                checkPoolExpiration();
045                
046                CtClass ctNewClass = _classSource.newClass(name, superClass);
047                
048                return new ClassFabImpl(_classSource, ctNewClass);
049            }
050            catch (Exception ex)
051            {
052                throw new ApplicationRuntimeException(EnhanceMessages.unableToCreateClass(name, superClass, ex), ex);
053            }
054        }
055    
056        /** @since 1.1 */
057    
058        public InterfaceFab newInterface(String name)
059        {
060            try
061            {
062                checkPoolExpiration();
063                
064                CtClass ctNewClass = _classSource.newInterface(name);
065    
066                return new InterfaceFabImpl(_classSource, ctNewClass);
067            }
068            catch (Exception ex)
069            {
070                throw new ApplicationRuntimeException(EnhanceMessages.unableToCreateInterface(name, ex), ex);
071            }
072    
073        }
074    
075        public void resetEventDidOccur()
076        {
077            if (_classCounter >= EXPIRED_CLASS_COUNT)
078            {
079                _classCounter = 0;
080    
081                _pool = new HiveMindClassPool();
082                _classSource.setPool(_pool);
083            }
084        }
085    
086        void checkPoolExpiration()
087        {
088            _classCounter++;
089        }
090    }